73 



TABLE 44. — STEM CORRECTION FOR CENTIGRADE THERMOMETER 22 



22 Taken from Smithsonian Meteorological Tables. 



TABLE 45.— REDUCTION OF GAS THERMOMETERS TO THERMODYNAMIC 



SCALE 



The final standard scale is Kelvin's thermodynamic scale, independent of the properties 

 of any substance, a scale resulting from the use of a gas thermometer using a perfect gas. 

 A discussion of this is given by Buckingham, 22 * "The thermodynamic correction of the 

 centigrade constant-pressure scale at the given temperature is very nearly proportional 

 to the constant pressure at which the gas is kept" and "the thermodynamic correction to 

 the centigrade constant-volume scale is approximately proportional to the initial pressure 

 at the ice point." These two rules are very convenient, since from the corrections for any 

 one pressure, one can calculate approximately those for the same gas at any other pressure. 



The highest temperature possible is limited by the container for the gas. Day and 

 Sosman carried a platinum-rhodium gas thermometer up to the melting point of palladium. 

 For most work, however, the region of the gas thermometer should be considered as ending 

 at about 1000°C (1273°K). 



Note : All corrections in the following table are to be added ahjcbraically. 



22 « Bull. Nat. Bur. Standards, vol. 8, p. 239, 1912. 



SMITHSONIAN PHYSICAL TABLES 



